Using a linearly chirped seed suppresses SBS in high-power fiber amplifiers, allows coherent combination, and enables long delivery fibers
Abstract
When seeding a high power fiber amplifier with a frequency-chirped seed, the backward Brillouin scattering can be kept at the spontaneous level because the coherent laser/Stokes interaction is interrupted. Operating a conventional vertical cavity surface-emitting diode laser in an optoelectronic feedback loop can yield a linear frequency chirp of ~1016 Hz/s at a constant output power. The simple and deterministic variation of phase with time preserves temporal coherence, in the sense that it is straightforward to coherently combine multiple amplifiers despite a large length mismatch. The seed bandwidth as seen by the counter-propagating SBS is large, and also increases linearly with fiber length, resulting in a nearly-length-independent SBS threshold. Experimental results at the 600W level will be presented. The impact of a chirped seed on multimode instability is also addressed theoretically.
Additional Information
© 2014 Society of Photo-Optical Instrumentation Engineers (SPIE). This work was supported by the High Energy Laser Joint Technology Office under contract 11-SA-0405 and the U.S. Army Research Office under grant W911NF-11-2-0081.Attached Files
Published - 896102.pdf
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Additional details
- Eprint ID
- 101484
- DOI
- 10.1117/12.2042919
- Resolver ID
- CaltechAUTHORS:20200224-084930942
- 11-SA-0405
- High Energy Laser Joint Technology Office
- W911NF-11-2-0081
- Army Research Office (ARO)
- Created
-
2020-02-24Created from EPrint's datestamp field
- Updated
-
2021-11-16Created from EPrint's last_modified field
- Series Name
- Proceedings of SPIE
- Series Volume or Issue Number
- 8961